Why does cabin heat matter for a device?
Electronics have an operating range and a storage range. A cab that stands in the sun for hours can pass both. The usual signs are a device that restarts in the afternoon, a recorder that stops writing to its card, and a backup battery that swells.
Gulf summers make this a design question, not a rare event. The checker gives a planning estimate so you can choose the spot and the device rating before the install.
How is the peak estimated?
Cabin air rises fast in the first hour, then levels off. The spot adds its own offset, and the margin covers stronger sun.
- The rise curve comes from a 2010 study of parked cars: 21.5 °C on average in 60 minutes, and 65 °C inside at 33 °C outside. That study ran in the United States, so the margin field covers stronger Gulf sun.
- The dashboard offset and the sunshade effect come from a University of Baghdad study that measured about 70 °C cabin air and close to 100 °C on the dashboard in summer.
- All model values and offsets are page settings that Tracom staff can update.
Which mounting spot runs coolest?
Out of the sun and away from the glass is almost always cooler. Spots marked as assumptions are planning values, not measurements.
| Spot | Offset | Sun-exposed | Basis |
|---|---|---|---|
| Top of the dashboard | +30 °C | Yes | Study, University of Baghdad |
| Windscreen, behind glass | +15 °C | Yes | Assumption, measure |
| Cab ceiling | +5 °C | No | Assumption, measure |
| Under the dash | 0 °C | No | Assumption, measure |
| Behind the seats | 0 °C | No | Assumption, measure |
| Under a seat | -5 °C | No | Assumption, measure |
| Chassis in shade | ambient +10 °C | No | Assumption, measure |
A GNSS or cellular antenna may need a view of the sky. The device box does not. Mount the box under the dash and run the antenna cable to the glass.
What about backup batteries?
Lithium-ion cells have a narrower charging range than their discharge range. Battery University gives 0 to 45 °C for charging as a typical figure, and many chargers stop charging above about 50 °C.
A hot cab is not only a risk for the cell. It also means the battery may not be full when the vehicle loses main power. Use the value on your battery datasheet.
How do you measure your own cab?
Place a logger
Put a small temperature logger at the planned spot, and one on top of the dashboard for comparison.
Record a hot week
Leave them for a week in July or August with normal parking.
Enter the offset
Compare the spot with the cabin and ask Tracom staff to update the offset, or use the margin field.
Assumptions and limits
- The estimate is for a closed vehicle parked in full sun. Open windows, tinted glass and colour change the result.
- Device heat is not added. A device that is on adds its own heat inside its box.
- Engine bays are outside this estimate.
- Device, battery and card limits are your inputs. The starting values are typical examples, not Tracom specifications.
- Sources and date checked 2026-11-03: the 2010 study (21.5 °C average rise in 60 minutes; 65 °C inside at 33 °C outside), the University of Baghdad study (about 70 °C cabin air, dashboard near 100 °C, a windscreen shade cut the dashboard rise by 40 %) and BU-410 (Li-ion charging 0 to 45 °C). These are studies and a reference site, not standards.
This is not a temperature test or a qualification. For a tender clause or a warranty question, use the device datasheet and a measured log.